Device for blocking passage of a fluid in a defined direction through a tubular part provided in particular in a household appliance operating with a fluid, through which part the fluid can be conducted in the direction opposite to the defined direction, the device comprising a check valve which has a sealing element and a contact region serving as a valve seat and formed in a fluid passage of the tubular part. The invention further relates to a household appliance which operates with a fluid and in particular to a dishwashing machine having a device as disclosed above.
Devices of the aforementioned type which are equipped with a check valve are employed in appliances operating with a fluid, in particular in household appliances, in order to enable a fluid to flow in only one fluid direction in a fluid passage containing the respective check valve. In the direction opposite to the flow direction in question, the respective check valve must meanwhile exert a sealing effect so that no fluid flow is possible in the corresponding opposite direction. This presupposes a precise matching fit of the respective sealing element at an associated contact region. It should be noted that what is to be understood by a fluid in this context is a liquid or a gas.
In a known device of the type considered hereintofore (DE 698 18 391 T2), a shunt check valve is provided in a shunt drain system of a dishwasher, said shunt check valve being located at an outlet of a pump chamber and being movable between a closed position and an open position in response to a pressure difference between its two sides. The shunt check valve in question consists of a carrier part formed by a pump chamber and having a drain conduit to which a tubular part of the shunt drain system is connected, and of a pivotable saucer-shaped valve element which is connected to said drain conduit and cooperates with a valve seat provided around the drain conduit in question to form a seal. However, this design requires an assembly technology for implementing the said shunt check valve which is sometimes considered undesirable. This is because the said valve element must be installed in the said drain conduit of the relatively voluminous and awkwardly shaped pump chamber, which is a labor-intensive task. Furthermore, the elements forming the shunt check valve must satisfy relatively high requirements in terms of accuracy of fit. The use of a device separate from the said pump chamber for forming a check valve is, however, not provided in the case of the known shunt drain system in question.
In order to block fluid passages in dishwashers it is also already known (DE 34 43 166 C2, DE 100 17 243 A1) to provide check valves (non-return valves) in the respective fluid passages, which valves in each case comprise a ball accommodated by a valve seat of a conduit and in sealing contact with its valve seat. By means of the check valves thus formed a fluid can then flow through the respective check valve in only one flow direction in each case; in the opposite direction thereto the respective check valve prevents a fluid flow. Because of the valve balls that are required in each case therein and that have to be ground with high precision, such check valves are sometimes regarded as too complicated and too expensive in manufacturing terms. There is therefore the desire to seal a tubular part through which a fluid is to be conducted so reliably by means of an easy-to-manufacture and easy-to-install check valve that a passage of fluid through the tubular part in question is made possible in only one flow direction, whereas it is reliably blocked in the opposite direction thereto.